"I’m embargoed from releasing details until tomorrow. But I can say that the new plan will be across-the-board with supply-side incentives from rate reduction, and that it will help small-business owners as well as everyone else," wrote Kudlow, who is a columnist and economics editor for the conservative magazine's website.

Romney hinted at his plans Tuesday at a town hall in Shelby Township, Mich. He said that he had laid out "some of the beginnings" of his ideas on taxes, spending and entitlements in his 2011 book Believe in America. "On tax policy, I said I want to see taxes flatter, and fairer and simpler, because I want our tax policies to encourage growth. I'm going to be elaborating on that some more over the next couple of days," Romney said.

Romney said he will also talk about "more things to reduce in our spending to get our budget annually balanced. And then finally, our entitlements and obligations. I'm going to get more specific about some of the things we need to do to protect Medicare and Social Security for coming generations."